The proposed research is designed to demonstrate the efficacy of Phase-Modulated Near Infrared Spectroscopy (NIRS) in the in-vivo detection of cerebral oxygenation levels by quantitatively measuring cerebral oxygenated hemoglobin (Hb02) and de-oxygenated hemoglobin (Hb). This research also will build a foundation for human studies and the eventual commercialization of this technology, particularly in neonatal applications. The specific research plan is to evaluate a Phase Modulated NIRS instrument recently built by InnerVision Diagnostics by completing tests on a series of non-human models. the specific aims are: 1.) to compare the concentrations of a compound as determined by Phase-Modulated NIRS with its known concentration in a static phantom brain model. 2.) to compare the concentrations of oxy- and deoxy- hemoglobin concentration and hemoglobin-02 saturation in a dynamic phantom brain as determined by Phase-Modulated NIR spectroscopy with co- oximetry. 3.) to compare the concentrations of oxy- and deoxy - hemoglobin concentration and hemoglobin- 02 saturation in a piglet brain as determined by Phase-Modulated NIR spectroscopy with co-oximetry. 4) To provide recommendations on how instrumentation can be advanced to address any limitations discovered in the course of this study.